This actually worked, but I wouldn't try it the same way again.
We took two "spectrum" kids on the regular guided tour of Wind Cave National Park.
One of them was on the verge of bolting for the half the 60 minute tour, then he settled down. The other was tearful, anxious and had his ears covered and eyes largely closed for about 50 minutes, though after 30 minutes he was doing better. By the last 10 minutes he was almost ready to start.
It's very hard to exit one of these tours. You need a guided escort to take the elevator hundreds of feet to the surface. Yes, it was a bit much for our guys. They need a more gradual introduction. We should have started with the small-time gaudy tourist-trap type caves that are easy to enter and exit. Then we could have worked up the to the real thing.
It can be done though. Not saying it should be done ... this way.